Cathode ray tubes



Sept. 5, 1967 G. J. BARZ ETAL 3339;777

CATHODE RAY TUBES Filed March 6, 1963 Ill!!!)lllllllllllili I INVENTORSGUNTER J. B|ARZ JOHANNES .v KUFFER HUGO HAIDER HELMUT s. THIELE JOHANNES0. FR. RITTER BY wgg g ATTORNEYS United States Patent 3,339,777 CATHODERAY TUBES Giinter J. Barz, Johannes Kiiifer, and Hugo Haider, Ulm(Danube), Helmut Thiele, Senden filler), and Johannes Ritter,Herrlingen, Germany, assignors to Telefunken Patentverwertungs-Gm.b.H.,Ulm (Danube), Germany Filed Mar. 6, 1963, Ser. No. 263,152 Claimspriority, application Germany, Mar. 8, 1962, T 21,718; Mar. 21, 1962, T21,798 25 Claims. (Cl. 220-21) The present invention relates to cathoderay tubes.

More particularly, the present invention relates to an implosionprotective device for cathode ray tubes, such as television picturetubes, as well as to a method for manufacturing such implosionprotective device. The implosion protective device comprises a rigidframe which encompasses the tube in the region of its largest diameterand is spaced therefrom, the interspace between the frame and the wallof the tube being occupied by a filler mass which, when cold, is itselfrigid.

It is known to equip a tube with a rigid frame which surrounds the tubein the region of its largest diameter, which frame firmly grips the tubethereby to lessen the consequences of an implosion which may result fromdamage to the tube. It is also known to use the frame for mounting thetube within a housing. The frame is generally secured to the wall of thetube by means of a filler mass. This filler mass between the tube walland the frame, which latter is ordinarily made of metal, is, forexample, sulphur, gypsum, or cement.

The present invention provides new filler masses which have a number ofadvantages over the heretofore known filler masses. According to thepresent invention, there is provided a filler mass having the followingcharacteristics:

(a) The material stays solid up to a temperature of at least 80 C.

(b) The material is highly liquid at temperatures of betweenapproximately 100 C. and 180 C., and preferably at temperatures ofbetween 135 C. and 150 C.

(c) While the material is in solid state, there is no volatilizationwhich causes odors or corrosion.

(d) The material sets or hardens within a short period.

(e) The material does not undergo an appreciable volumetric change as itgoes from liquid to solid state.

The filler mass may also be constituted by sand, preferably with binder,or by a mixture that contains at least 20% sand.

A television tube equipped with a protective device according to theinstant invention is illustrated in the accompanying drawing in whichthe single figure is a sectional view of a thus-equipped tube.

As shown in the drawing, the cathode ray tube, which may be a televisionpicture tube 1, is equipped with a frame 2 which surrounds the tube inthe region of its maximum circumference. The frame comprises two annularpull-exerting bands or straps 2a, 2b, which have peripheral flanges 3a,3b, that are firmly connected to each other as, for example, by means ofa channel-shaped fold. In practice, the front strap 2b is so configuredas to outline the viewing screen of the cathode ray tube.

The frame is somewhat larger than the outer diameter of the tube so thateven those picture tubes which are within the prescribed tolerances-alittle oversized will still be readily accommodated within the frame. Inorder firmly to secure the frame to the picture, tube, the interspace 4between the frame and the wall of the tube is filled with a filler mass.This filler mass can be introduced into interspace 4 by letting it flow,while in liquid state, from the conical side of the tube into theinterspace. In order to stop the flow of the liquid material, the strap2b may carry suitable sealing means such as sealing rings 5.

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Under certain circumstances, it has been found desirable to provideadditional sealing means 5a to close off the other end of theinterspace, which sealing means are put in place after the filler masshas been poured into the interspace. In this way, the filler mass can beprotected against external influences, as, for example, humidity.

The straps 2a, 2b, may be made of any suitable material, such as metal,or the frame may be a single preformed plastic part made of a polyesterglass fiber mixture. According to another feature, the sealing meansconsist of a cement which is fashioned, for example, into the shape ofan annular bead which is placed into the front strap 2b. In this way,the tube presses against the cement bead and thus seals the spacebetween the tube and frame at the point of engagement. Under certaincircumstances, it is desirable to place further sealing means 6 betweenthe flanges 3a and 3b so as to prevent the filler material, which isstill highly liquid when it flows into the interspace 4, from seepingout of the seam of the flange. The sealing means 6 may consist, forexample, of a cement, a glue,

an adhesive, or the like.

It has been found important that the filler mass itself does not causeany vapor pressure. This means that the material consisting the fillermass must be such that, in the region of the operating temperature ofcathode ray tubes, which region is up to approximately C., there must beno evaporation or volatilization effect which could give rise toobjectional consequences, such as the formation of odors and thegeneration of corrosive vapors. If, for example, the filler mass issulphur, the same will volatilize and attack the circuit elementsordinarily used with cathode ray tubes.

It has also been found that the filler mass of the above type should nothave too high a melting point. The material should be highly liquidbetween C. and 180 C., and preferably between the narrower range of C.to C., furthermore, the material should be such that, uponsolidification, it undergoes as small a volumetric change as possible.In particular, the material should be of such a nature that it does notshrink upon solidification.

It has also been found advantageous to addcolor pigments to the fillermass, in order to prevent, for example, a picture tube which is not inuse from appearing in different colors due to reflection effects. Thepigments may, for example, be black color pigment.

The following are examples of filler masses according to the presentinvention, all of which have the abovedescribed characteristics.

EXAMPLE 1 The filler mass consistsof urea to which salicyclic acid orbenzoic acid as well as wax, bitumen and kieselguhr (diatomaceous earth)are added. The salicyclic or benzoic acid serves to make the filler massless Water soluble and to prevent the decomposition of the molten urea.The wax and kieselguhr also reduce the water solubility. The filler massmay also have added to it solid particles such as" cuttings or shavings,as, for example, mechanical wood pulp, sand, or porcelain powder, theporcelain powder, for example, additionally acting as crystallizationnucleus.

As an example the following filler masses may be 3 EXAMPLE 2 bitumenpolyethylene wax EXAMPLE 3 The filler mass consists of colophony with asoftening agent for instance of Percent by weight (a) colophony 80-90triphenylphosphate 10-20 (b) colophony 80-90 diphenylcresylphosphate10-20 EXAMPLE4 The filler mass consists of chlorinated naphthaline. Theamount of chlorination in the naphthaline is not critical. Anychlorinated naphthaline as it is sold by many companies can be used.

EXAMPLE 5 sugar kieselguhr EXAMPLE 6 The filler mass consists of alum towhich cuttings or shavings are added. In the case of such a filler massthe additional sealing means at the edges have been found to beparticularly advantageous. The filler mass may consist for instance ofPercent by weight (a) alum 70-80 sand 20-30 (h) alum 70-80 porcelainpowder 20-30 EXAMPLE 7 The filler mass consists of phthalic (acid)anhydride to which cuttings are added as for instance of Percent byweight (a) phthalic anhydride 70-80 sand v 20-30 (b) phthalic anhydride70-80 porcelain powder 20-30 EXAMPLE 8 The filler mass consists ofbetanaphthol to which cuttings are added as for instance of Percent byweight (a) betanaphthol 70-80 sand 20-30 (h) betanaphthol 70-80porcelain powder 20-30 EXAMPLE 9 The filler mass consists of chlorinatedpolyethylene to which cuttings are added as for instance of Percent byweight chlorinated polyethylene 95-99 kieselguhr 1-5 4 EXAMPLE 10 Thefiller mass consists of paraflin with wax additives and cuttings as forinstance of Percent by weight (a) parafiin -99 hard wax l-10 (b)parafiin 90-99 hard wax 105 l-10 triphenylphosphate 1-5 Each of theabove-mentioned filler masses has the characteristic that it becomeshighly liquid (highly liquid being intended to refer to a liquid havinga viscosity of 20-100 centipoise, preferably 30-80 centipoise, at atemperature of between 100 C. and 180 C., and generally between about C.and C., and they can, in such liquid state, readily be poured into theinterspace between the frame and tube wall. The liquids solidify veryrapidly (within approximately 5-20 minutes), without appreciableshrinkage, and form a firm contact mass between the frame and tube wall.Thanks to the mentioned additives, the filler masses are relativelyinsensitive to water and water vapors and, above all, will not produceany objectionable volatilization. It is particularly advantageous toprovide the solid additives mentioned above, namely, the cuttings orshavings, with the sand being especially suitable because it issubstantially insensitive to the temperatures to which the tube issubjected during the manufacturing stages. Furthermore, the sand willnot produce any vapors or gases.

It has also been found desirable to mix a filler mass consistingsubstantially of sand with a binder, which, under appropriate treatment,solidifies and thus firmly binds the sand particles to each other sothat, upon setting of the binder, the filler mass will be a solid massconsisting of sand and binding agent. The thus-obtained solidifiedfiller mass produces the desired rigid connection between the frame andthe tube.

The sand is, suitably, first cleaned and dried. The binding agent canbe, for example, synthetic resins, wax, or the filler masses accordingto the present invention. The binding agents can be hot or cold settingagents; also, the binding agents can be in liquid or powder form. It isalso possible to fill the interspace between the tube and frame entirelywith pure sand, in which case, however, a good sealing compound orgrouting will have to be provided at the edges of the frame. Inpractice, it is better if the sand has a binder homogeneously admixedwith it.

The implosion protective device according to the present invention canbe manufactured as follows: The sand is admixed with a powdered binder,which mixture is then introduced into the interspace between the frameand the tube, whereafter the mass is treated in such a manner as to meltthe binder so that the latter firmly binds the sand particles.

Alternatively, the sand can be soaked in a liquid binder, as, forexample, a synthetic resin solution of low viscosity. Here it ispossible either first to pour the binder into the interspace andthereafter to introduce the sand, or first to let the sand flow into theinterspace and thereafter to let the binder soak into the sand.

According to another method, the sand can be wetted with a liquid binderand then dried, whereafter the fragments obtained in this manner arereduced to small pieces and screened, the thus-prepared sand then beingintroduced into the interspace. The mass is then set generally by heattreatment. The sand is suitably very fine-grained (the grain size beingof the order of approximately 400- 2000 microns) so that it can betrickled into the interspace. A better fill factor may be obtained ifthe sand has different size grains.

In the methods in which the sand is mixed with a liquid binder, a largequantity of binder will generally be needed in order completely to fillthe interspaces between the individual sand particles. If the protectivedevice is made by a method in which the sand is first appropriatelyprepared, i.e., a method in which the surfaces of the sand particles arepowdered or coated with the binder and thereafter introduced into theinterspace between the tube and frame, a subsequent heat treatment willcause the prepared sand particles to be bound to each other. Thismethod, too, will produce a relatively rigid mass which, however, hasair pockets and therefore contains a low proportion of binder. It ispossible, in this way, to make do with approximately 4% binder. It isalso possible to influence the setting time of the binder byappropriately heating the sand.

A main advantage of the described filler masses are to be seen in theirresistivity against moisture. The disadvantages of gypsum and cementconsist in the fact that these materials need much water to becomeliquid enough for pouring into the interspace. After gypsum or cement isin the solid state it needs much time to eliminate the water out of thesolid filler mass. Furthermore cement often becomes chappy.

It will be understood that the above description of the presentinvention is susceptible to various modifications, changes, andadaptations, and the same are intended to be comprehended within themeaning and range of equivalents of the appended claims.

What is claimed is:

1. An implosion protective device for cathode ray tubes comprising arigid frame encompassing the tube in the region of its maximum diameterand being spaced from the wall of the tube, so as to form an interspacetherebetween, and a set filler mass in said interspace, said filler massbeing a material which remains solid up to a temperature of at least 80C., which is highly liquid at temperatures of between approximately 100C. and 180 C., which, while in solid state, does not volatilize toproduce odorous or corrosive vapors, which sets quickly, and whosevolume remains substantially unchanged as it goes from liquid to solidstate.

2. A device as defined in claim 1 wherein said filler mass material ishighly liquid at temperatures of between approximately 135 C. and 150 C.

3. A device as defined in claim 1 wherein said filler mass material isresistive to water and water vapors.

4. A device as defined in claim 1 wherein said filler mass materialcontains color pigmentation.

5. A device as defined in claim 1 wherein said frame has an edgeconfigured to outline the viewing screen of said tube, there being asealing ring made of cementing material arranged between said edge andsaid tube.

6. A device as defined in claim 1 wherein said filler mass materialconsists of urea having at least one additive.

7. A device as defined in claim 6 wherein said filler mass material hasadded to it wax, kieselguhr, and an acid selected from the groupconsisting of salicylic acid and benzoic acid.

8. A device as defined in claim 1 wherein said filler mass materialconsists of bitumen and an additive selected from the group consistingof wax and synthetic resins.

9. A device as defined in claim 1 wherein the filler mass materialconsists of hardened colophony and a softening agent.

10. A device as defined in claim 1 wherein said filler mass materialconsists Of Chlorinated naphthaline.

11. A device as defined in claim 1 wherein said filler mass materialconsists of solidified sugar.

12. A device as defined in claim 1 wherein said filler mass materialconsists of alum.

13. A device as defined in claim 1 wherein said filler rnass materialconsists of phthalic anhydride.

14. A device as defined in claim 1 wherein said filler mass materialconsists of betanaphthol.

15. A device as defined in claim 1 wherein said filler mass materialconsists of chlorinated polyethylene.

16. A device as defined in claim 1 wherein said filler mass materialconsists of parafiin and wax.

17. A device as defined in claim 1 wherein said filler mass material hassolid cuttings admixed with it.

18. A device as defined in claim 17 wherein said cut tings are selectedfrom the group consisting of wood pulp, porcelain powder and sand.

19. A device as defined in claim 17 wherein said cuttings aredistributed substantially homogeneously through out said filler mass.

20. A device as defined in claim 1 wherein said filler mass contains airpockets.

21. A device as defined in claim 1 wherein said frame is made of metal.

22. A device as defined in claim 1 wherein said frame is pre-fonned andis made of a polyester glass fiber mixture.

23. A device as defined in claim 1 wherein said frame is made of asingle piece.

24. A device as defined in claim 1 wherein said frame is made of amaterial selected from the group consisting of metal and plastics, andwherein said frame comprises two interconnected flanged parts.

25. An implosion protective device for cathode ray tubes comprising arigid frame encompassing the tube in the region of its maximum diameterand being spaced from the wall of the tube so as to form an interspacetherebetween, and a set filler mass in said interspace, said filler massbeing selected from the group consisting of sand, a mixture containingat least 20% sand, and a material which remains solid up to atemperature of at least C. which is highly liquid at temperatures ofbetween approximately C. and C., which while in solid state, does notvolatilize to produce odorous or corrosive vapors, which sets quickly,and whose volume remains substantially unchanged as it goes from liquidto solid state.

References Cited UNITED STATES PATENTS 227,389 5/ 1880 Sawyer 2202.1

503,108 8/1893 Bates .1 220-21 1,647,695 11/ 1927 Hawley 264-2612,091,615 8/1937 Rohm et al 264-261 2,500,384 3/1950 Schell 220-2.12,671,822 3/1954 McMahon 264-261 2,785,820 3/ 1957 Vincent et al.

OTHER REFERENCES German printed application, Philips, 1,117,158, Nov.16, 1961.

THERON E. CONDON, Primary Examiner.

GEORGE O. RALSTON, Examiner.

M. L. RICE, Assistant Examiner.

1. AN IMPLOSION PROTECTIVE DEVICE FOR CATHODE RAY TUBES COMPRISING ARIGID FRAME ENCOMPASSING THE TUBE IN THE REGION OF ITS MAXIMUM DIAMETERAND BEING SPACED FROM THE WALL OF THE TUBE, SO AS TO FORM AN INTERSPACETHEREBETWEEN, AND A SET FILLER MASS IN SAID INTERSPACE, SAID FILLER MASSBEING A MATERIAL WHICH REMAINS SOLID UP TO A TEMPERATURE OF AT LEAST80*C., WHICH REMAINS SOLID UP TO A TEMPERATURES OF BETWEEN APPROXIMATELY100*C. AND 180* C., WHICH, WHILE IN SOLID STATE, DOES NOT VOLATILIZE TOPRODUCE ODOROUS OR CORROSIVE VAPORS, WHICH SET QUICKLY, AND WHOSE VOLUMEREMAINS SUBSTANTIALLY UNCHANGED AS IT GOES FROM LIQUID TO SOLID STATE.